Propeller Killer? High Efficiency Paddle Vs. Propeller

this video is sponsored by factor in my previous video of this homemade autonomous boat I failed at a 56 km or 35m Waypoint mission in the Salish sea this is the big ocean inlet near Seattle Washington the biggest issue was seagrass getting tangled in the propellers got a freaking sushi burrito here so in this video I'm going to test out some alternative methods of propulsion and see if they are capable of being as efficient as my standard boat propellers I've had issues with propeller fowling in quite a few of my previous videos and the armchair engineering experts in the comment section have come up with just about every solution possible here are some of the ones that I'm not going to test today razor sharp propellers could potentially work on a speedboat with faster spinning propellers but my propellers are big and spin slow for high efficiency for that reason they probably wouldn't be able to cut through weeds even if they were razor sharp large propellers on real boats are less prone to seagrass but they do have issues getting tangled in rope for this line Cutters are used on the prop shafts I'm not very confident that this sort of a thing would work for my application because the seagrass seems to accumulate on the prop blades themselves not just the shaft next up is wire mesh prop guards in order for wire mesh to keep out the thinnest of weeds it would need to be pretty fine and putting fine mesh around a propeller or really anywhere under the water line is just terrible for efficiency water jet propulsion is great for things like jet skis and river boats that need to operate in shallow water but compared to a normal propeller it's also very inefficient last up is the classic Paddle Wheel generally paddle wheels are less efficient than propellers but I think that if you made one big enough it could be pretty comparable in this video I going to to test what might be a more optimized but similar concept to the Paddle Wheel so after I had decided that I wanted to test alternative propulsion methods I headed back to the lake for one last test drive with the old propellers to collect some efficiency data we're going to be looking at wat hours per kilometer and this data is collected by the AR pilot Rover flight controller on board so after that I headed back home and removed the old drivetrain so the first alternative propulsion method I'm going to try out is a linkage driven paddle I got this idea after seeing some other online videos of people trying this out it looked pretty weed proof and efficient this mechanism has an advantage over regular old paddle Wheels because the path that the paddle takes through the water is more effective the geometry can also be adjusted to fine-tune the paddles entrance and exit out of the water to minimize drag I kind of think about it like a Paddle Wheel being compared to a highly inefficient walking gate and the linkage mechanism being more like a proper human walking gate I drew up this model in on shape that converts a rotary motion from a low KV brushless motor into the paddling motion on shape is a cloud-based CAD program that runs in your internet browser and it's free to hobbyists so if you want to download or modify my designs click on the link in the description and sign up for a free on shape account then you'll have full access to the mechanism and all the other designs in this video I 3D printed a lot of the parts out of Grey Pro resin on the form laabs form 3 plus and I fdm printed some of the bigger Parts I used my CNC router to cut out a paddle out of thin plywood that got a layer of varnish to make it waterproof I'm using 15 mm carbon tubes as the legs of the linkage okay this is my first time powering up the motor let's see what happens wow it's so smooth that's awesome this is [Music] forwards oh that's great what happens if we Crank It Up previously this boat steered using differential thrust with its two underwater propellers since it's only going to have one paddle it now needs a Rudder to steer I cut one out of some 8in acrylic and then 3D printed some little hinges for it and then glued those onto the back side of the hole after that it was time to head back to the lake for a test drive hey baby you like my autonomous boat oh yeah this paddle very well may be the next biggest Leap Forward for maritime efficiency since the days of Christopher Columbus but do you know what very well might be the next biggest leap and efficiency for your lifestyle it's Factor meals skip all those timec consuming trips to the grocery store and get factor factor lets you avoid the chopping prepping and cleaning up that comes with cooking while still getting the flavor and nutritional quality you need Factor's fresh never frozen meals already in Just 2 minutes so all you have to do is heat and enjoy then get get back to doing whatever you like to do sign up for factor and you get to choose from over 35 weekly flavor packed meals that promote a healthy lifestyle round out your meals and replenish your snack Supply with an assortment of 45 plus add-ons to suit your taste this month I tried some of their Protein Plus meals like spinach and mushroom chicken thighs Factory meals come in a refrigerated box with ice bags so you never have to worry about thawing them out or freezer burn like those frozen meals from the grocery store just pop them in the microwave for a minute and a half and they're ready to enjoy this one here is the peanut Buddha boy a great option for you vegetarians out there another one I tried this month is the queso fondito Not only was it delicious but it's also gluten-free head to factor 75.com or click on the link below and use code RC testflight 50 to get 50% off your first Factor box I had to do a little bit of paddle height adjustment so that it wasn't hitting the water on the backstroke it's scooting kind of scoots along wow going that a good clip yeah it's pretty fast it's so silly looking I was pleasantly surprised that this thing worked really well with hardly any adjustment it was even capable of going decently fast which I was not expecting at low and medium speeds the paddle looked like it was entering the water pretty smoothly with very little splashing which is good on the exits it looks like the paddle starts the return stroke a little too low because it was splashing a bit at higher speeds this was more visible it would also sometimes Splash on Entry but I think this was in part due to the boat pitching up and down with waves here I went to Full Throttle which put a lot of stress on the gears and Link es combine this with the paddle slapping into waves and it was enough Force to cause the gears to start skipping uh-oh it just started making a weird noise turns out one of the axles had just slid out of place it was an easy fix but I'd say this mechanism is only good for slow speeds it's definitely not robust enough for super high-speed driving with this program called motion gen we can visualize the exact path of the paddle takes through the water the cool thing about this program is that you can change the geometry and see how it affects the path in real time pretty useful for mechanical linkages like this what was your idea I thought the paddle needs to have a hinge so when it recovers forward it's going sideways through the air or water and it can uh waste a lot less energy so as per Colin's idea I integrated a flapper here a little pivot hinge onto the paddle so it cannot pivot this way but it can pivot on the return stroke we'll see how this works there it goes with the Hing installed the paddle would just fold back when it entered into the water this could also indicate that the paddle is mounted a bit too low and maybe mounting it higher would allow it to accelerate more closely to the speed of the vessel before it enters into the water it totally sucks at higher speeds the paddle would be folded during the entire return stroke and it wouldn't even have a chance to straighten out before entering the water I tried more rubber bands to stiffen up the hinge and that seemed to help a little bit you can still see the paddle pivoting on entry into the water maybe this is a good thing though tough to say I bet you if you do any fishen run it'll still be better you think yeah I do think well we can test that let's do it here's the efficiency data in milliamp hours per kilm it's really difficult to eyeball the average efficiency since the value spikes when the paddle is under the highest load I tried to smooth out the data by adding an RC filter on the current measurement signal wire but for some reason that didn't work I'll have to save that problem for later so the next day I printed new mounting brackets so that the paddle could be mounted up higher the paddle is even above the lowest point on the holes now so it can spin freely online land I would guess this will give us more efficiency but maybe less Peak thrust I don't know this dog just wants me to play fetch you can see how the paddle enters and exits the water super smoothly even at higher speeds it's way better than before at this point it even just seemed efficient there was very little splashing very little noise and all around it seemed like a very respectable propulsion system here's some slow motion 240 frame per second video of the paddle at the highest mounting position this is during acceleration and this is during sustained speed it still looks pretty good here's a front view it definitely looks like the paddle speed almost exactly matches the water speed as it enters that's great for efficiency there was a nice lady on Shore that was so stoked on how good the video from her new phone looked that she offered to send it to me so here it is thanks lady oh and it's uh remote controlled yeah wow so I did a bunch of different tests with the paddle I had it super high super low and everywhere in between also super floppy and fixed in place then I went home and analyzed all the rdpilot log data to fix the spikes in the current drop problem Sebastian added some filtering to this MAV Explorer efficiency equation and this is what we get nice smooth efficiency data I'm saving the grand efficiency data comparison for the end of this video since we still have one more propulsion method to test out this next one is maybe going to be slightly less interesting than the paddle but quite possibly more practical I've used air propellers on some of my autonomous boats in the past and they are just about as seaweed proof as it gets but the reason why I've shied away from them on recent builds is that they are quite a bit less efficient than underwater propellers this is true in most cases but it turns out that there are some exceptions I recently found out that the record holder for the world's fastest human powerered water vehicle uses an air propeller instead of a water propeller they're able to get away with this because the air propeller is absolutely huge turns out if your air propeller is big enough a 3 m diam in this case with a high enough coefficient of lift the efficiency can be as high as 90% furthermore the hardware associated with mounting an air propeller has negligible drag whereas the housing required for an underwater propeller has a significant drag penalty this part totally reminds me of what I found during my hydrofoil ground effect vehicle experiments having anything underwater at high speeds has a terrible drag penalty even if it's a Sleek hydrodynamic design it's best to have as little surface area touching the water as possible but anyways bigger propellers are generally more efficient than and smaller propellers this is true for both air and water propellers but it's more difficult to make a water propeller really big that's because you need a deeper hle or a deeper prop housing to accommodate it which both come with significant drag penalties so let's try out a huge air propeller this is the same 8108 100 KV multi-rotor motor that I was using on the paddle but now it's got a prop a 30-in prop that is that's pretty big it's hard to tell because of the camera frame rate and shutter speed but the prop is spinning quite slowly at a cruise speed of around one you can visibly see the propeller go round and round it took very little throttle to cruise nice and slow and when I would raise the throttle a bit it would get moving pretty quickly here I got up to 2 m/ second but the max speed is kind of irrelevant because I had the throttle pwm artificially capped so that I wouldn't pull too much current and burn something out I was using pretty small ESC on this thing but anyways the goal isn't speed it's efficiency and nothing's worse for efficiency than Towing around weeds I just can't get away from them they were stuck on the rudder and the prop protector fins for for the old underwater props so what did I do I went home and took the rudder off and then cut the fins off and sanded the holes Down Smooth then it was back to the lake but wait how am I going to steer without a Rudder aha differential thrust I added a second propeller so now we have double the disc area which is even more efficient than before check this out there was a Lake Steam tornado how neat is that the dual air propellers worked great no surprises here and now there's absolutely nothing on the bottom of the boat for weeds to get stuck on double the motors also means double fast it got up to 4 m/ second this time so finally the moment we've all been waiting for it's time to compare the efficiency data let's start off by looking at the different paddle configurations it's no surprise that the paddle was most efficient at its highest mounting position and at this position the pivoting paddle wasn't really doing that much the data shows that a rigid mounted paddle was maybe like 10% more efficient than the pivoting paddle but that difference could just be in the noise tough to say as for the air propellers the Dual propellers were this much more efficient than the single propeller pretty good so here's the grand compar between all three it turns out everything was better than the water propellers this sort of surprised to me but also sort of didn't the water propellers just have so much less disc area than the air propellers and the paddle although I guess you can't really call the paddle disc area also the water propellers have to transfer power through long shafts and stuffing boxes to keep the water from leaking into the holes with the air propellers we ditch all that inefficiency the biggest surprise here is probably that the paddle even beat the water propellers but I think it really comes down to surface area when it comes to aircraft design there's really no replacement for wingspan if you want to make a plane more efficient make its wingspan larger that's why I made the paddle as wide as possible there's less opportunity for the water getting pushed to just flow around the edges and create tip vortices I think that if we made a paddle with the same surface area as the water propellers have disc area then it would for sure be less efficient but our paddle is huge compared to the water propellers so it's just going to be more efficient the dual air propellers are clearly Superior so let's put them to use and retry the big Waypoint mission that this boat had previously failed okay it's off doing its own thing I got to be careful because there's Giants lurking in the shadows okay I got the boat launched we're heading out into the ocean and I think I see our autonomous friend out there so we got to go chase it down now there's a tugboat pulling a barge out there probably coming from Alaska there's the city skyline sticking up over the hill with Mount rineer pretty Majestic it's a lot more choppy out here than I was expecting especially considering that the wind forecast is like less than 5 mph all day that's weird hopefully it glasses off later what the heck this thing is doing circles that's weird well it's a good thing we're already here we can see what's wrong what the heck maybe a motor went out wa the props are hitting the water oh no whoa I did not expect the props to be hitting the water damn I guess it's too wavy for it out here that sucks Jiminy Christmas well I think we just failed the mission man look at that Sunrise all right let's put it back into auto mode and see if it behaves now I just took this big heavy battery off so hopefully that prevents the props from hitting the water oh there it goes ah they're still hitting the water then I tried taking off another battery at this point it probably wouldn't have had enough capacity on board to complete the whole Waypoint Mission keep it going then off you go I think I'm going to call it quits at that this Mission just failed because I did not anticipate it being this wavy out here here cuz the forecast called for super super calm winds today like as low as the wind forecast ever gets and yet it's still super wavy which is weird because I've been out here in the evenings when it's typically windier and seen it just be perfectly glassy before so very difficult to predict the waves out here I've had two fails in a row with this boat we need to get serious now design something that's really good so surely I could make this boat work by just moving the propellers up away from the water but I think I've just about milked this boat dry in terms of YouTube interest so the next time I attempt this Waypoint Mission will be with an entirely new boat design wow look at all the puffins wooo we're win millon baby that's pretty much it for this video but quickly one more thing my previous video was about testing pidal propellers versus normal propellers on my electric paddle board in that video I said that I was going to host a propeller design competition where I would print and test designs that viewers send in I just wanted to remind those interested in submitting a design to follow RC testflight on Instagram that's where I'll be posting more info on where and when to submit your designs thanks for watching bye that thing is just plowing the water wow also that's a super short little [Music] Tugboat oh that was a huge wake there's a big sea line or something out here oh there he is this guy's looking for some fish

Channel: rctestflight

Views: 207,653

Keywords: boat, ship, propulsion, propeller, paddle, efficiency, efficient

Id: ox6ZXrrK8yE

Length: 16min 28sec (988 seconds)

Published: Tue Dec 19 2023